Beliefs:
	/* The cost represents how much longer would be the route of elevator if it included
	   the new stop. Random part is added to decide ties automatically.
	 */
	cost(CurrentPlan, NewStop, _, Cost) :- newStopCost(CurrentPlan, NewStop, NewStopCost), 
	                                       Cost is (NewStopCost + rand).
	
	                                       
	                                       
